1. Field of the Invention
The present invention relates to a document pressing device which stably presses a particularly thick document against a document table and a document pressing method.
2. Description of the Related Art
When a conventional electrophotographic copying machine, printer or the like reads a thick document supported by a document table, to prevent defective reading due to leakage of light or a displacement of the document, the document is pressed from above a document cover by an operator to prevent the document from becoming loose or a hinge which is an opening and closing fulcrum of the document cover is vertically moved according to a thickness of the document and an opening and closing side of the document cover is also engaged with a pressure-applying member of a main body to hold the document cover horizontal to press the document as disclosed in Japanese Patent Application Laid-Open No. 4-268546.
Between the aforesaid document pressing methods, however, the former case is very poor in operability because the operator must keep pressing the document cover while an image is being read. The latter case does not require the operator to keep pressing the document cover and its operability is improved. But, the operation to fix the document cover took time because the opening and closing end of the document cover must be fixed to a pressure-applying member while adjusting a height of the opening and closing side of the document cover in order to fix the document cover horizontal to press the thick document.
Therefore, it is desired to improve operability of the document cover by facilitating and simplifying its fixing operation to securely press the document against the document table and to prevent the document from being displaced or exposure light from leaking at the time of reading even when the document placed on the document table is thick.
It is an object of the present invention to obtain a good reading image while preventing a displacement of a document or leakage of exposure light when a document having a large thickness is placed on a document table and read.
It is another object of the present invention to obtain high operability by facilitating and simplifying the fixing operation to hold the document cover horizontal in order to securely press the thick document to the document table by the document cover.
According to the present invention, it provides a document pressing device, comprising document supporting means mounted on a main body for supporting a document; document covering means for covering the document supporting means and pressing the document against the document supporting means; adjusting means for supporting an opening/closing fulcrum of the document covering means and being slidable in a thickness direction of the document according to the thickness of the document supported by the document supporting means; holding means which can hold an opening and closing side of the document covering means for sliding in the thickness direction of the document in synchronization with the sliding movement of the adjusting means; engaging means disposed on the opening and closing side of the document covering means for engaging with the holding means to give the document covering means a pressing force for pressing the document against the document supporting means; and engagement releasing means for releasing the engagement of the engaging means from the holding means.
The present invention also provides a document pressing device, comprising a document table disposed on a main body to support a document; a document cover which covers the document table to press the document against the document table; an adjusting hinge configured to support an opening/closing fulcrum of the document cover and being slidable in a thickness direction of the document according to the thickness of the document supported by the document table; a holding member which can hold an opening and closing side of the document cover to slide in the thickness direction of the document in synchronization with the sliding movement of the adjusting hinge; a hook disposed on the opening and closing side of the document cover to engage with the holding member to give the document cover a pressing force to press the document against the document table; and a release member to release the engagement of the hook from the holding member.
Besides, the present invention provides a document pressing method for pressing a document against a document table by covering the document placed on the document table mounted on a main body by a document cover, comprising the steps of an adjusting step to slide an opening and closing fulcrum of the document cover in the thickness direction of the document according to a thickness of the document supported by the document table and slide a holding member for holding an opening and closing side of the document cover in the thickness direction of the document in synchronization with the sliding movement of the opening and closing fulcrum; an engaging step to engage a hook fitted to the document cover with the holding member to press the document against the document table by the document cover; and a releasing step to release the engagement of the hook from the holding member.